Not so much more corrupting than the Taint of Bhaal, just think of it as synergestic.what I wouldn't give for an edit button....
But about the corrupting a PC, you mean somehow Valen is going to have a more corrupting influence then the taint of Bhaal? I guess its possible, but I don't see it as very likely. I think someone who has been successfully living and overcoming the taint of Bhaal for their entire life would probably be able to deal with something as simple as a vampire's mind games. Though of course refering back to my previous post, nothing wrong with adding OPTIONS to the mod for people who want to take advantage of them.
It's also potential for her to approach the corruption in a manner different from how the Protagonist has been facing the beast in the past.
Thing about options, is that they still redefine the character. Which is where the problem comes down to, and I really agree that Valen should be kept as an evil psychopathic killer, to do elsewise, cheapens her.